It is known from for instance U.S. Pat. No. 6,382,907 to provide a cooling system for such a component, which includes first and second ribs placed on the first wall and second wall, respectively, i.e. on the suction side and the pressure side, at different inclination angles in relation to the rotary axis of the machine and in relation to the flow direction of the cooling air. The ribs form a matrix of channels for the cooling fluid flowing through the component. The ribs connect at their intersections to each other and to a central plane of the component. In this prior art document, the component has a leading set of ribs and trailing sets of ribs which either are connected to each other or are divided from each other.
Although this prior art cooling system is able to provide an efficient cooling of the component, it may happen, in case the cooling fluid is not perfectly clean, that foreign particles in the cooling fluid may be caught in the matrix. In a worse scenario, some of the matrix channels can be plugged close to the trailing edge, thus reducing the cooling performance of the system. Furthermore, since the ribs are joined at the central plane of the component, the height of the cooling channels is merely 50% of the total height, i.e. distance between two walls of a component, available for the cooling system. This is especially critical at the trailing edge of the component, where the height of the cooling passage is the smallest in the whole component.
SU-A-1228559 discloses a rotor blade for a rotary machine. The blade comprises an inner space, forming a passage for a cooling fluid and limited by first and second walls facing each other. Ribs project form said walls and extend substantially in parallel to each other to form first channels for said fluid from a leading inlet part of the inner space to a trailing outlet part of the inner space. The ribs are divided into a leading set of ribs in the leading inlet part and a trailing set of ribs in the trailing outlet part. The leading set of ribs extend in a first direction forming a first angle of inclination to the rotary axis of the machine in said leading part. The trailing set of ribs extend in a second direction forming a second angle of inclination to the rotary said axis in said trailing part. The trailing end of some of the ribs in the leading set of ribs are following a curved path to have a decreasing angle of inclination.
RU-C1-2042833 discloses another blade for a rotary machine. The blade comprises an inner space, forming a passage for a cooling fluid and limited by first and second walls facing each other. Ribs project form said walls and extend substantially in parallel to each other to form first channels for said fluid from a leading inlet part of the inner space to a trailing outlet part of the inner space. The ribs are divided into a leading set of ribs in the leading inlet part and a trailing set of first ribs in the trailing outlet part. The leading set of ribs extend in a first direction forming a first angle of inclination to the rotary axis of the machine in said leading part. The trailing set of ribs extend in a second direction forming a second angle of inclination to the rotary said axis in said trailing part. The first angle is clearly smaller than the second angle.
U.S. Pat. No. 3,806,274 discloses a rotor blade for a gas turbine, which has first ribs on an inner wall and opposite second ribs on an opposite wall. However, the first and second ribs are separated from each other by an insert plate in such a way that the flow channels formed between the first ribs are completely separated from the flow channels form between the second ribs.